Since we have shown garter snakes capable of developing antibody following experimental infection of Western equine encephalitis, as measured by a modified neutralization test, the study to determine the duration of antibody response has been continued. Attempts are made to establish the identification and serological relationship of field viral isolates from ticks and mosquitoes using a variety of techniques such as hemagglutination, hemagglutination , inhibition, complement-fixation, neturalization, and fluorescent-antibody. The laboratory has continued to assist in the surveillance of encephalitis viruses and certain rickettsial disease agents in Montana and in other states when requested by providing virus isolation and serodiagnostic services to physicians and veterinarians.